Mixer devices



July 26, 1966 N. ROTHMAN MIXER DEVICES Filed March 1?. i964 United States Patent O 3,262,681 MIXER DEVICES Nathan Rothman, London, England, assignor to Silverson Machines Limited, London, England, a British company Filed Mar. 17, 1964, Ser. No. 353,661 Claims priority, application Great Britain, Mar. 21, 1963, 11,343/ 63 15 Claims. (Cl. 259-115) This invention relates to mixer devices suitable for use with materials which, when subject to mixing, give olf noxious gases or infectious bacteria.

In medical research it is sometimes necessary to prepare a mixture of materials which include infected animal tissue or to disintegrate an infected organ or other substantial part of a body. It is then essen-tial that mixing or disintegrating be carried out under conditions which prevent the escape of noxious gases and bacteria into the surrounding atmosphere.

According to the .present invention a mixer device suitable for mixing or disintegrating materials which, when subject to mixing or disintegration, give off noxious gases or infectious bacteria, comprises a supporting head for securing a mixing vessel relative to the frame of a driving motor, a shaft which extends through the head and is so arranged that, when the ves-sel is secured relative to the frame by the head, oneend olf the shaft is coupled to an output shaft of the motor and the other end is disposed within the vessel, rotor means secured to the end of the sha-ft disposable within the vessel and adapted upon rotation of the shaft to eect mixing or disintegration of material within the vessel and sealing means which serve to ensure that the head and vessel co-operate to form -a gas-tight enclosure.

The sealing means may include a collar through which the shaft `extends and which is rotatable with the shaft, a sealing element arranged to prevent the escape of gas an-d bacteria between the collar and the shaft, and means for urging the collar axially 'relative to the shaft into contact with a part of the device which is xedly secured relative to the supporting head, contactingvsurfaces of the collar and the said 'part of the device being adapted to prevent the escape of gas and bacteria therebetween.

Preferably the mixer device includes stator means which are secured to the head and are so arranged that rotation of the rotor means causes material within the vessel to be drawn axially into the stator means and then expelled outwardly through the stator means in directions normal to the axis of the shaft.

The invention fwill now be described, `by way of example, with reference to the accompanying drawings, in which:

FIGURE 1 shows a driving motor and casing of a mixer according to the invention, partly in section;

IFIGURE 2 is an axial section of a mixer device according to the invention for use with the motor and casing of FIGURE l; and

FIGURE 3 is a reaction vessel for use with the mixer device of FIGURE 2.

The mixer shown in the drawings is for use in a laboratory Where animal tissues are infected and then disintegrated. During this process noxious gases and bacteria may be released from the tissues and it is essential to prevent these from escaping into the atmosphere. Co-operating rotor and stator means 1 and 2, respectively, of the mixer device 3 shown in FIGURE 2 are therefore mounted on a supporting head 4 which `forms the lid for an open-topped reaction vessel 5, shown in FGURE 3 and sealing means 6 are provided on the hea-d to ensure that the head and vessel co-operate to form a gastight enclosure. The head 4 is also adapted to be mount- 3,252,631 Patented July 26, 1966 ICC ed in a fixed position relative toa driving motor 7, see FGU-RE 1, in which position an output shaft 8 of the motor is coupled to a shaft 9 carrying the rotor means of the device.

As indicated in FIGURE l the driving motor 7 and an associated control rheostat 11 and main switch 12 are mounted in a casing 13 which is provided with a horizontally extending arm (not shown) for attachment to a bench stand. Both the rheostat 11 and the main switch 12 are electrically connected together in series with a Wi-nding of the motor 7 and both are operable [by means of controls extending exteriorly of the casing, variation of the rheostat control varying the speed of the output shaft 8 of the motor.

With the mixer mounted in its operative position the output shaft 8 of the motor 7 extends downwardly through an aperture in the bottom of the casing 13, the lower end face of the shaft being formed with an axially extending central recess 14. The part of the shaft 8 bel-ow the casing is provided with a sleeve 16 which extends downwardly a short distance below the end of the shaft and is formed with two diametrically opposed, axially extending slots 17 at its lower end. Between the slots 17 the wall of the sleeve 16 is cut back so that its length decreases uniformly in one angular direction from one slot to the other. The central recess 14 in the output shaft 8 of the motor is for locating the shaft 9 bearing the rotor of the mixer device and the sleeve 16 is for relea-sably locking the two shafts together, as will be described hereinafter.

A hollow, cylindrical supporting member 18 is secured to the bottom of the casing .13, co-axially of the output shaft 8, by means of screws 19 which extend uplwardly into the casing through an inwardly extending flange at the upper end of the member. yExteriorly of the supporting member 18 is a movable locking sleeve 21 for securing the head 4 of the mixer device to the casing 13. A stop screw 22 extends through the wall of the sleeve '21 and has its inner end in engagement with an axially extending groove 23 in the wall of the supporting mem- Iber 18, the amount of axial movement of the sleeve relative to the member being determined by the length of the groove. The bottom ofthe sleeve 2\1 is bevelled at its inner edge and on movement of the sleeve downwardly the bevelled surface bears against locking balls 24 disposed in apertures in the wall of the sup-porting member, urging them inwardly into engagement with the head, as will be described hereinafter.

Referring to FIGURE 2, the head 4 of the mixer device 3 is of generally cylindrical shape and includes an upper, hollow portion 26 adapted to be secured to the supporting member 18 on the casing 13, a central flange 27, and a lower portion 28 which forms a lid for the reaction vessel. The stator means 2 of the device include a tube 29 which extends dorw-nwardly from the lower portion 28 of the head and the rotor means 1 is at the lower end of a shaft 9 which extends upwardly through central apertures in the lower portion 28, central flange 27, and a lbottom wall 31 of the upper port-ion 26 of the head.

The upper portion 26 of the head is of extrnal diameter substantially equal to the internal diameter of the supporting member 1'8 on the casing shown in FIGURE l and of 'length smaller than the `length of that member. A short distance above the central ange 27 is a circumferential groove 32, which, when the upper portion 26 is pushed up into the supporting member 18 and the sleeve 21 is moved downwardly, receives the locating balls 24. Engagement between the -balls 24 and the groove 32 prevents relative axial movement between the head and suporting member) thereby xedly securing the mixer device to the casing of the motor.

, manner described above the tapered end of the rotor shaft 'locates in the central recess 14 of the motor output shaft 8 and the driving pins 33 are received by the vrespective slots 17 in the sleeve 16 on the output shaft. Owing to the wall of the sleeve being cut back, as described above rotation of the output shaft in one sense only will cause rotation of the rotor shaft, and hence of the rotor secured thereto.

For supporting the reaction vessel of FIGURE 3 below the head 4 of the mixer device there is provided a U-shaped clamping frame 34 having an inwardly extending pin 36 at the upper end of each of its arms. The spacing between the arms is substantially equal to the diameter of the lower portion 28 of the head and they can be bent outwardly to -allow the pins 36 to enter radially opposed sockets 37 in the wall of the lower portion. Engagement between the pins 36 and sockets 37 prevents relative movement between the frame 34 and head 4 axially of the head.

A clamp screw 3S extends through the base of the clamping frame 34 and at its upper end carries a supporting plate 39 for the reaction vessel 5. Rotation of the screw 38 causes axial movement of the vessel, urging its open, upper end upwardly into contact with a sealing ring 41 on Ithe lower face of the supporting head 4.

With the reaction vessel 5 in its mounted position the rotor shaft 9 extends downwardly from the head of the mixer device almost to the bottom of the vessel. The rotor means 1 itself consists of a flat disc 42 disposed in a horizonal plane normal to the axis of the shaft 9 and having four blades 43 extending downwardly therefrom. Each blade is disposed in a plane norm-al to the plane of the disc and is angularly spaced from adjacent blades by 90.

The tube 29 of the stator means 2 of FlGURE 2 is of internal diameter substantially equal to the diameter of the volume swept by the rotor blades 43 upon rotation of the rotor shaft 9 and of such length that its lower end is disposed a short distance below the bottom of the blades. A short distance above the lower end of the stator tube 29, on a level with the rotor blades, a series of circular apertures 44 are formed in the wall of the tube and act as outlets for material expelled from the rotating blades. Immediately above the disc 42 supporting the blades a small inner tube 46 of internal diameter `vsubstantially equal to the diameter of the rotor shaft 9 is secured to the interior of the tube 29 to provide a bearing for the lower end of the shaft and to inhibit flow of material upwardly. Above the inner tube the tube 29 is formed with two diametrically opposed, axially extending slots 47 which provide access to the interior of the tube for cleaning purposes.

The central apertures in the power portion 23 and central flange 27 of the supporting head 4 provide a working clearance for the rotor shaft 9 whilst the aperture 48 in the bottom wall 31 of the upper portion 26 is larger. Within this larger aperture 43 the shaft 9 is embraced by a collar 49 which is xedly secured to the head by forcing its lower end into an annular recess at ythe bottom of the aperture. At its upper end the collar 49 has a flange which, in the assembled position of the collar, bears downwardly on to a sealing ring 51 disposed at the bottom of the aperture. The ring 51 serves to prevent the escape of gas and bacteria from the vessel between the collar 49 and the head 4.

Above the fixed collar 49 is a movable collar 52 formed with a ange at its lower end and provided with a neoprene sealing ring 53'for preventing the escape of gas between the collar and shaft. The movable Vcollar 52 is urged downwardly so that the lower face of its flange is in contact with the upper face of the flange on the fixed collar 49 by a -coiled compression spring 54 whose upper end bears against a further flanged collar 56 secured near to the upper endy of the shaft 9. Upon rotation of the shaft 9 the further flanged collar 56, spring 54 and movable collar 52 are also caused to rotate whilst the fixed collar 4 9 remains stationary. Contacting surfaces of the xed and movable collars are made of a hard material and `are ground so that even upon relative rotational movement the escape of gases and bacteria between them is prevented. When the head 4 is removed from the casing 13 lubricant for these surfaces can be inserted through the open upper end of the head.

To operate the mixer material to be disintegrated is placed in the reaction vessel 5 and the latter lis placed on the supporting plate 39 of the clamping frame 34. The rotor and stator parts of the devices are then lowered into the vessel, the pins 36 at the upper end of the clamping frame 34 are located in their sockets 37 on the head, and the head is then secured to the vessel by rotating the screw 3S at the base of the clamping frame. To secure the head 4 to the motor casing 13 its upper portion 26 is pushed up into the supporting member 18 below the casing and locked in position by moving the locking sleeve 21 downwardly. With the head in this position the upper end of the rotor shaft 9 is coupled to the output shaft 8 of the motor and mixing can be commenced by switching on the motor and adjusting the speed of its output shaft by means of the rheostat 11.

Upon rotation of the rotor blades 43 material disposed `below them in the reaction vessel is drawn upwardly into the lower end -of the stator tube and is then expelled outwardly in directions normal to the axis of the tube 29, through the circular apertures 44 formed therein. As the material leaves the blades and impinges against the wall of the stator tube it is subjected to violent shearing forces Vwhich effect thorough mixing and disintegration.

Noxious gases and infectious bacteria released from the material during mixing and disintegration may cause the pressure within the reaction vessel 5 to rise above the pressure outside, the resulting pressure differential tending to urge the movable collar 52, compression spring 54, flanged collar 56 and the shaft 9 in an axial direction relative to the head 4 and fixed collar 49. However, axial movement of the shaft and collar 56 is prevented by the engagement of the shaft with the output shaft 8 of the motor and movement of the movable collar 52 relative to the collar 56 is prevented by the compression spring 54. Accordingly there is no relative axial movement tbeween the fixed collar 49 and movable collar 52 and escape of gas and bacteria between these collars, and hence between the shaft 9 and head 4, is prevented. Escape of gas and bacteria between the reaction vessel 5 and the head 4 is prevented by the sealing ring 41.

At the end of the mixing and disintegration process the locking sleeve 21 is moved upwardly, the head 4 and reaction vessel 5 are removed from the motor casing 13, and the mixed and disintegrated material is usually allowed to settle down in the vessel before further tests are carried out thereon.

With the shaft 9 no longer engaged by the output shaft 8 of the motor it might be expected that the compression spring 54 would be free to expand and move the flanged collar 56 and shaft 9 in an axial direction relative to the head 4 until the spring was no longer compressed. The

excess pressure within the reaction vessel 5 would then move the movable collar 52, compression spring 54, flanged collar and shaft 9 relative to the head 4 until the collar 52 had moved out of Contact with the fixed collar 49, thereby allowing noxious gases and bacteria to escape between the shaft and the head.

To prevent this escape of gas the clearance between the disc 42 of the rotor means 1 and the inner tube 46 is made smaller than the amount by which the spring 54 is compressed so that upon axial movement of the shaft 9 the disc engages the tube 46, to prevent further movement, whilst the spring is still compressed. The movable collar S2 is therefore continually urged into contact with the tixed collar 49 and escape of gas between the shaft 9 and the head 4 is prevented even though the head is released from the motor casing 13.

It will be appreciated that the open end of the vessel can be formed with a screw thread which co-operates with a corresponding thread on the lower portion of the head to secure the two together, thereby removing the need for a clamping frame. Suitable sealing means are provided to ensure that the seal between the head and vessel is gas-tight.

I claim:

1. A mixer device suitable for mixing or disintegrating materials which, when subject to mixing or disintegration, give off noxious gases or infectious bacteria, comprising a supporting head adapted to secure a mixing vessel relative to the frame of a driving motor in a manner which allows release of the head from the frame whilst the vessel remains secured to the head, a shaft which extends through the head and is so arranged that, when the vessel is secured relative to the frame by the head, one end of the shaft is coupled to an output shaft of the motor and the other end is disposed within the vessel, rotor means secured to the said other end of the shaft and adapted, upon rotation of the shaft to effect mixing or disintegration of material within the vessel, and sealing means which serve to ensure that the head and the vessel cooperate to form a gas-tight enclosure when the head is secured relative to the frame during mixing or disintegration and also after release of the head from the frame at the conclusion of mixing or disintegration.

2. A mixer device as claimed in claim 1, wherein the sealing means includes a collar through which the shaft extends, the said collar being rotatable with the shaft but movable in an axial direction relative thereto, a sealing element arranged to prevent escape of gas between the collar and the shaft, biasing means adapted to urge the collar in an axial direction relative to the shaft and towards a part of the device which is xedly secured relative to the head, whereby when the said one end of the shaft is coupled to the output shaft of the motor and the axial location of the shaft relative to that of the supporting head is thereby xed the collar is urged into Contact with the said part, contacting surfaces of the collar and the said part being adapted to prevent escape of gas and bacteria therebetween, and means adapted, when the shaft is decoupled from the output shaft so that relative axial movement can take place between the shafts, to limit axial movement of the shaft to a position wherein the collar remains in contact with the said part land the escape of gas and bacteria between the colar and the said part continues to be prevented.

3. A mixer device as claimed in claim 2, wherein the means for limiting axial movement of the shaft comprise co-operable elements respectively secured relative to the shaft and the head.

4. A mixer device as claimed in claim 2, wherein the means for urging the collar axially relative to the shaft is a helical compression spring arranged co-axially of the shaft with one of its ends bearing against an abutment on the shaft and its other end bearing against the collar.

5. A mixer device as claimed in claim 4, wherein the part of the .device contacted by the collar is a second collar through which the shaft also extends, the second collar being provided with a sealing element for preventing the escape of gas and bacteria between the second collar and the head.

6. A mixer device as claimed in claim 5, wherein the second collar is formed with a flange and the sealing element associated therewith is a sealing ring which is compressed between the flange and part of the supporting head.

7. A mixer device as claimed in claim 1, wherein stator means are secured to the head and are so arranged that rotation of the rotor means causes material within the vessel to be drawn axially into the .stator means and then expelled outwardly through the stator means in directions normal to the axis of the shaft.

8. A mixer device as claimed in claim 7, wherein the rotor means include a flat disc secured to one end of the shaft and disposed in a plane normal to the axis thereof, and a plurality of blades extending normally to the plane of the disc on the side thereof remote from the shaft, and the stator means include a tube which extends from the head co-axially of the shaft and is of internal diameter substantially equal to the diameter of the disc, apertures for the expulsion of material by the rotor means being formed in a side wall of the tube adjacent the blades.

9. A mixer device as claimed in claim S, wherein a sleeve of internal diameter substantially equal to the diameter of the shaft is secured to the inner wall of the tube, on the side of the disc remote from the blades, to inhibit flow of material along the interior of the tube.

10. A mixer device as claimed in claim 9, wherein the tube is formed with slots at locations intermediate the head and the rotor means to provide access for cleaning purposes.

11. A mixer including a mixer device as claimed in claim 1, and further comprising a driving motor mounted within a -casing with an output shaft thereof extending through an aperture in a side wall of the casing, and means for securing the supporting head of the device to the casing so that, with the head in its secured position, the shaft which extends through the head is coupled to the output shaft of the motor.

12. A mixer as claimed in claim 11, wherein a portion of the head remote from the rotor means is of cylindrical form, and the securing means include a hollow cylindrical member adapted to receive the cylindrical portion of the head, and locking means for locking the head to the cylindrical member so as to prevent relative movement therebetween in a direction axially of the shaft.

13. A mixer as claimed in claim 12, wherein an annular groove is formed in an outer surface of the cylindrical portion of the head, and the locking means include a plurality of balls located in respective -apertures in a side wall of the cylindrical member, and a sleeve disposed exteriorly of the member and movable axially thereof to a locking position in which they urge the balls inwardly into engagement with the groove on the cylindrical portion of the head, thereby preventing relative axial movement between the head and the member.

14. A mixer `as claimed in claim 13, wherein a sleeve the length of the sleeve decreases uniformly with angular4 distance in one angular direction from one slot to the other.

References Cited by the Examiner UNITED STATES PATENTS 4/ 1906 Benjamin 308-36.2 6/1944 Strauss 259-122 X FOREIGN PATENTS 1,117,546 11/ 1961 Germany.

WILLIAM I. PRICE, Primary Examiner. 

1. A MIXER DEVICE SUITABLE FOR MIXING OR DISINTEGRATING MATERIAL WHICH, WHEN SUBJECT TO MIXING OR DISINTEGRATION, GIVE OFF NOXIOUS GASES OR INFECTIOUS BACTERIA, COMPRISING A SUPPORTING HEAD ADAPTED TO SECURE A MIXING VESSEL RELATIVE TO THE FRAME OF A DRIVING MOTOR IN A MANNER WHICH ALLOWS RELEASE TO THE HEAD FROM THE FRAME WHILST THE VESSEL REMAINS SECURED TO THE HEAD, A SHAFT WHICH EXTENDS THROUGH THE HEAD AND IS SO ARRANGE THAT, WHEN THE VESSEL IS SECURED RELATIVE TO THE FRAME BY THE HEAD, ONE END OF THE SHAFT IS COUPLED TO AN OUTPUT SHAFT OF THE MOTOR AND THE OTHER END IS DISPOSED WITHIN THE VESSEL, ROTOR MEANS SECURED TO THE SAID OTHER END OF THE SHAFT AND ADAPTED, UPON ROTATION OF THE SHAFT TO EFFECT MIXING OR DISINTEGRATION OF MATERIAL WITHIN THE VESSEL, AND SEALING MEANS WHICH SERVE TO ENSURE THAT THE HEAD AND THE VESSEL COOPERATE TO FORM A GAS-TIGHT ENCLOSURE WHEN THE HEAD IS SECURED RELATIVE TO THE FRAME DURING MIXING OR DISINTEGRATION AND ALSO AFTER RELEASE OF THE HEAD FROM THE FRAME AT THE CONCLUSION OF MIXING OR DISINTEGRATION. 